Typically, two types of electric lamps have been utilized in the above applications. One such lamp, referred to in the art as a PAR (parabolic aluminized reflector) type lamp, typically utilizes a glass reflector and separate glass cover in which is positioned a coiled tungsten filament. A base member secured to the reflector is designed for being positioned within the required socket to provide the necessary connection to a power source (e.g., 120 VAC) for lamp operation. Examples of such lamps are illustrated in U.S. Pat. Nos. 4,506,316 (Thiry et al), 4,484,254 (Puckett et al) and 4,473,872 (Puckett et al), all of which are assigned to the same assignee as the instant invention.
A second type of lamp of this variety includes a quartz or high silica glass envelope having therein a coiled tungsten filament and also including a base member located on the envelope, the base designed for being positioned within a socket as mentioned above. Lamps of this type are referred to in the lighting field with such product designations as R20 (the R standing for reflector), R30, R40, ER30 (the ER standing for ellipsoidal reflector) and ER40. Examples of such lamps are illustrated in U.S. Pat. Nos. 4,041,344 (LaGiusa), Re. 30,832 (LaGiusa) and 4,331,901 (Vrijer et al).
While lamps of the above type do provide what are considered adequate illumination levels to the subject area, effective pattern control of this illumination is deemed inadequate. In addition, such lamps are considered to be relatively large (e.g., some having a bulb diameter exceeding four inches) and thus typically require the occupancy of correspondingly large volumes in their final environment (e.g., within a fixture), in turn requiring a large housing or the like to accommodate same. With particular regard to the latter type lamps (e.g., ER30), these lamps are also considered to be readily susceptible to damage (e.g., during handling) due to the relatively thin nature of their glass envelopes.